What Are Lung Cancer Biomarkers?

Lung cancer biomarkers, also known as tumor markers, are biological molecules in people with lung cancer. These biomarkers are produced by either the body or the tumor. 

Testing biomarkers helps characterize tumor growth and cancer spread. Biomarkers can be used to assess your risk of developing cancer, determine your risk of recurrence, predict the effectiveness of a cancer treatment, and monitor the progression of lung cancer. 

This article will define what cancer biomarkers are and explain how they are used in lung cancer treatment. 

Definition of Cancer Biomarkers

Cancer biomarkers are molecules produced by the body that give us a picture of the processes taking place inside your body. While biomarkers are helpful for learning more about an individual’s cancer, they can also be used to learn more about heart disease, multiple sclerosis, and other chronic conditions.

Lung cancer biomarkers are any substances in the body produced by cancer cells or other cells in response to cancer. These markers can tell us how aggressive the cancer is, what kind of treatment will be most effective, and whether an individual is responding to the current treatment protocol. 

Cancer biomarkers can be detected in the blood, urine, stool, tumors, or other body tissue and fluids. 

Cancer biomarkers can include:

• Proteins
• Changes in genes (mutations)
• Extra copies of genes
• Missing genes

Cancer biomarkers are usually classified by their function.

Driver Mutations

Cancer biomarkers can help the medical team detect driver mutations in the body. Each of our cells is made up of thousands of genes. These genes contain DNA that tells the cell how to function. When a gene experiences an error in its DNA, a mutation can occur.

Usually, the body corrects mutations, but when it cannot, a tumor may form. Mutations that cause a cancerous tumor to form are called driver mutations. Specific biomarkers can show which mutation caused cancer and, thus, which treatment will be most effective. 

Immunotherapy

Cancer biomarkers can also help the medical team determine if immunotherapy drugs will be helpful for treating lung cancer. The immune cells in the body have proteins on their surfaces that act as checkpoints. These proteins prevent the immune system from overreacting. 

An example of an immune checkpoint is the PD-L1 protein. This protein usually helps the immune system function normally. However, in the case of lung cancer, the cancer cells sometimes contain a large number of PD-L1 proteins. These proteins essentially put the brakes on the immune system and prevent immune cells from fighting cancer cells. 

When an individual tests positive for the biomarker PD-L1, the medical team can prescribe immunotherapy drugs that boost the immune system response and help it attack cancer cells.

Uses of Cancer Biomarkers

The use of biomarkers has forever changed lung cancer treatment. In the past, two people with the same type of cancer received the same treatment. Thanks to cancer biomarkers, physicians can now individualize treatment plans based on which therapy is most effective against each tumor. 

The two main types of tumor markers are circulating tumor markers and tumor tissue markers. Circulating markers circulate through the body in the blood, urine, stool, or other bodily fluids. They can be used to estimate an individual’s prognosis, determine the stage of cancer, find residual disease, detect recurrence, assess treatment effectiveness, and monitor treatment progress. 

Tumor biomarkers can be found via biopsy (a procedure that removes tissue for testing in a lab) in the tumor itself. These specific biomarkers are used for the same purposes.

Your medical team may recommend obtaining serial measurements of biomarkers throughout the course of your cancer treatment.

When testing for biomarkers in lung cancer, the medical team looks for abnormalities in the DNA of the tumor. Since these abnormalities are not inherited, you are not expected to pass them down to your children. The abnormalities found in lung cancer are believed to be caused by environmental factors like cigarette smoke or exposure to chemicals like radon or asbestos. 

Biomarker tests your physician may recommend include:

• EGFR mutation analysis: Epidermal growth factor receptors, known as EGFRs, are structures found on the surface of certain cells that receive messages about growing and dividing. On a cancer cell, these receptors have a mutation that causes them to continue to grow and divide without stopping. By testing for this specific mutation, the medical team can then determine if a patient would benefit from drugs that turn off these receptors. A common example of an EGFR inhibitor drug is Tagrisso (osimertinib). 
• ALK testing: Like EGFR, the anaplastic lymphoma kinase (ALK) gene also tells tumor cells to grow and divide. Testing for this mutation helps the medical team choose the right treatment. 
• Proteomic testing: This blood test is typically used in people who have been diagnosed with advanced non-small cell lung cancer. The test is called VeriStrat and can help predict how an individual will respond to an EGFR inhibitor. This test only requires a blood sample, so no tumor biopsy is needed. 
• KRAS mutation analysis: Many forms of lung cancer have tumors with a mutation in the KRAS gene.
  
• ROS1 rearrangement: ROS1 gene mutation or rearrangement can be found in people with certain types of non-small cell lung cancer. This abnormality is found in cancer cells in the tumor tissue. 
• BRAF V600E mutation: This type of mutation is used to determine the treatment for lung cancer. 
• NTRK fusion: This test is performed to determine treatment, especially for people with stage 4 lung cancer. 
• MET amplification or MET exon 14 skipping: This abnormality is seen most often in adenocarcinoma, a type of lung cancer. It helps to determine treatment and monitor its effectiveness.
• RET arrangements: This abnormality helps determine treatment in stage 4 lung cancer. 
• PD-L1: This test is used to determine if immune checkpoint inhibitor therapy would be helpful in treatment.
• Liquid biopsy test: This test is used to look for mutations in fragments of tumor DNA circulating in the blood.

One limitation of cancer biomarkers is that they cannot diagnose cancer on their own. They are one tool used during the diagnostic process but cannot produce a definitive answer alone.

Lung cancer is detected through a thorough diagnostic process, which includes a physical exam, detailed history, lung biopsy, lymph node biopsy, and imaging studies such as an X-ray, computed tomography (CT) scan, and magnetic resonance imaging (MRI). A positron-emission tomography (PET) scan will also be ordered.

Lung Cancer Biomarkers in Treatment and Research 

Once your doctor has determined your cancer biomarkers, the doctor will then use the latest research to identify which treatments are most likely to work for your individual type of cancer. 

Biomarker tests for lung cancer include:

• FISH analysis: The pathologist, a medical specialist, examines a tissue sample under a microscope to look for changes in the chromosomes. 
• Immunohistochemistry: The pathologist examines cells under a microscope to look for certain proteins.
• Next-generation sequencing: Also known as comprehensive biomarker testing, this test uses tissue taken from a tumor biopsy and places it in a machine that tests for several biomarkers at once.
• Liquid biopsy: This test can detect tumor DNA that has “leaked” from the tumor into the blood. This is helpful because it allows doctors to study the tumor makeup with a simple blood test. 

New research on biomarkers is ongoing. Currently, the Food and Drug Administration (FDA) has approved targeted therapies for lung cancer treatment for tumors with abnormalities in:

• EGFR
• ALK
• ROS1
• BRAF V600E
• MET
• RET
• NTRK
• Her2

Abnormalities in EGFR, ALK, ROS1, BRAF V600E, MET, RET and NTRK are usually found in people with adenocarcinoma. Once your medical team understands which biomarkers are present, they will select targeted therapies proven to address each one. Targeted therapies are a type of biological cancer treatment that attacks certain cells. 

In addition, immunotherapy is approved for use in people with an abnormality in PD-L1. Immunotherapy is another form of biological cancer treatment that boosts the immune system’s response to fight cancer cells. 

Summary

Lung cancer biomarkers are molecules in the body produced by cancer cells or by healthy cells in response to cancer. Biomarkers have revolutionized cancer treatment and given individuals the opportunity to receive personalized treatment plans. 

A Word From Verywell

A cancer diagnosis is scary, and you may be feeling understandably overwhelmed right now. As you work with your doctor to understand your diagnosis and treatment options, ask about biomarker testing. It’s helpful to remember that cancer research is always evolving, and there may be new tests and treatments available now.